BUG: Raise RuntimeError when reloading numpy is attempted.

There seems to be little use in reloading numpy as any changed modules
that are imported into numpy would need to be reloaded first in order to
see any changes. Furthermore, reloading causes problems as global
classes defined in numpy/__init__.py change their identity. Hence we
raise a RuntimeError when an attempt to reload numpy is made.

Closes #7844.

1 files changed, 26 insertions, 0 deletions

diff --git a/numpy/tests/test_reloading.py b/numpy/tests/test_reloading.py
new file mode 100644
index 000000000..141e11f6c
--- /dev/null
+++ b/numpy/tests/test_reloading.py
@@ -0,0 +1,26 @@
+from __future__ import division, absolute_import, print_function
+
+import sys
+
+import numpy as np
+from numpy.testing import assert_raises, assert_, run_module_suite
+
+if sys.version_info[:2] >= (3, 4):
+    from importlib import reload
+else:
+    from imp import reload
+
+def test_reloading_exception():
+    # gh-7844. Also check that relevant globals retain their identity.
+    _NoValue = np._NoValue
+    VisibleDeprecationWarning = np.VisibleDeprecationWarning
+    ModuleDeprecationWarning = np.ModuleDeprecationWarning
+
+    assert_raises(RuntimeError, reload, np)
+    assert_(_NoValue is np._NoValue)
+    assert_(ModuleDeprecationWarning is np.ModuleDeprecationWarning)
+    assert_(VisibleDeprecationWarning is np.VisibleDeprecationWarning)
+
+
+if __name__ == "__main__":
+    run_module_suite()